The evolution of the windshield wiper for vehicles has progressed from a traditional frame supported wiper into a modern non-framed wiper, colloquially called as flat blade wiper. The frame supported wiper usually includes a U-shaped metal strip called a metal blade frame with a lengthwise slot in the frame for holding a rubber blade to serve as an exposed supporting keel for the associated rubber blade, whereas a flat metal strip for the non-framed wiper is imbedded in a soft elastic clipping sleeve sheath, which actually holds a rubber blade, to serve as an enveloped keelson for the associated rubber blade. Recently, most windshield wipers having been used by the newly marketed vehicles are non-framed wipers. The frame supported wiper have apparently become phased out in the market because it involves more components with heavier weight and more power consumption, and after certain service time is susceptible to corrosion due to weatherworn effects of the exposed metal blade frame. Moreover, the windshield wiper is a consumptive products, requiring replacement when its wiping function declines due to aging which may affect the driving safety. The accumulative quantity of the eliminated defective wipers from annual replaced frame supported wiper might become a heavy burden for the environment protection. Contrarily, there are no such foregoing drawbacks for the non-framed wiper.
Accordingly, various non-framed wipers such as USA utility patents in numbers of U.S. Pat. No. 6,523,218, U.S. Pat. No. 6,944,905, U.S. Pat. No. 7,228,588, U.S. Pat. No. 7,055,206, U.S. Pat. No. 7,305,734, U.S. Pat. No. 7,484,264 and U.S. Pat. No. 7,210,189 as well as USA new design patents in numbers of D430097, D512362, D457479, D443854, D511735, D5644345, D5649555, D5794015 and D5798495 have been developed. Among those non-framed wipers mentioned above, the U.S. Pat. No. 7,210,189 patent disclosed a newest non-framed wiper as shown in FIGS. 1 through 6. As known from the “Detailed Description of Preferred Embodiment of the Present Invention” in the published patent specification, the windshield wiper comprises two blade bodies 6, a flat metal vertebra 7 with rectangular cross section, a rubber element 9 and a central support 10 wherein:
Said blade body 6 consists in a flexible upper support 4 and a semi-rigid lower support 5. Joining the upper support 4 and the lower support 5 by co-extrusion assures the single piece formed an integral support to the other components of the blade system including the metal vertebra 7 and the rubber element 9, in which, said upper support 4 includes a mounting channel 8, passing lengthwise throughout the length of the blade body 6, being preferably rectangular in shape, inside of which the metal vertebra 7 is inserted, also having preferably rectangular and flat profile and shape, being used for securing and keeping the element 9 in uniform contact with the windshield 3, said lower support 5 includes a lower mounting channel 12, passing lengthwise throughout the length of the blade body 6, being preferably rectangular in shape and further provided with a longitudinal rectangular opening 13 extending throughout the blade body 6, in which the rectangular upper section 16 with central neck of the rubber element 9 is inserted through the rectangular upper section 15 and the longitudinal rectangular opening 13 (as shown in FIGS. 1 through 3); and
Said central support 10, which is made of metallic or plastic material to be adjusted to the adapter of wiper arm 2 of the windshield wiper 3, comprises an upper mounting channel 11 and a lower passage channel 14 such that said upper mounting channel 11, passing lengthwise throughout the length of the central support 10, being preferably rectangular in shape, and said passage channel 14, passing lengthwise throughout the length of the central support 10, being preferably rectangular in shape inside of which the metal vertebra 7 is inserted, and further provided beneath with a longitudinal rectangular opening 15 extending throughout the sequential central support 10, in which the rectangular upper section 16 of the rubber element 9 is inserted through (as shown in FIGS. 2 and 3).
Please refer to FIGS. 2 through 6, which describes the assembly procedure for the conventional windshield wiper of the prior art in the U.S. Pat. No. 7,210,189 patent. Firstly, pass the mounting channel 11 of the central support 10 through the metal vertebra 7 up to the central position thereof, then fix the central support 10 at the central position of the metal vertebra 7 by bolts or rivets (as shown in FIG. 6); Secondly, insert each end of the metal vertebra 7 into corresponding mounting channel 8 in the upper support 4 of the blade body 6 (as shown in FIG. 4) so that each half of the metal vertebra 7 is enveloped by a blade body 6 (as shown in FIG. 6); and Finally, insert each rectangular upper section 16 of the rubber element 9 into corresponding lower mounting channel 12 and passage channel 14 and the longitudinal rectangular opening 13 and 15 on the blade body 6 and the central support 10 (as shown in FIG. 5), so that the entire windshield wiper is successfully assembled (as shown in FIG. 3).
However, some drawbacks exist in the conventional windshield wiper of the prior art in the U.S. Pat. No. 7,210,189 patent as below:
As shown in FIGS. 7 through 7e, when the rubber element 9 is pushed over the windshield 3 by the wiper arm 2, a normal force component Fv exerts on the blade body 6 so that the wiping edge of the rubber element 9 is tightly pressed against the top surface of the windshield 3 (as shown in FIG. 7); Because the wiper arm 2 swings back and forth during rain, the metal vertebra 7 has a forward horizontal force component Fh exerting on the blade body 6 (as shown in FIG. 7a) upon wiper arm 2 swinging forth, whereas the metal vertebra 7 has a backward horizontal force component Fh′ exerting on the blade body 6 (as shown in the hypothetical line of the FIG. 7c) upon wiper arm 2 swinging back; Thereby, action of the forward horizontal force component Fh and the backward horizontal force component Fh′ will indirectly apply to the rubber element 9 orderly via the flexible upper support 4 firstly and semi-rigid lower support 5 secondly of the blade body 6 so that the wiping edge of the rubber element 9 will wipe over the top surface of the windshield 3 to achieve the wiping effect. During forward horizontal force component Fh exerting on the blade body 6 by the metal vertebra 7, the right side of the upper mounting channel 8 in the soft flexible upper support 4 of the blade body 6 will be laterally affected by the right side of the metal vertebra 7 in contact pushing manner while the left side of the upper mounting channel 8 will not be laterally affected by the left side of the metal vertebra 7 in detached manner (as shown in FIG. 7a); Because action of the forward horizontal force component Fh and the backward horizontal force component Fh′ will indirectly apply to the rubber element 9 orderly via the upper support 4 and lower support 5 of the blade body 6 so that the wiping edge of the rubber element 9 will wipe over the top surface of the windshield 3, therefore, when wiper arm 2 swings forth, the right side of the upper mounting channel 8 in the soft flexible upper support 4 will be deformed in stretchable manner due to squeeze by the by the right side of the metal vertebra 7 while the left side of the upper mounting channel 8 in the soft flexible upper support 4 will be deformed in a gap 8 left between the left side of the upper mounting channel 8 and the left side of the metal vertebra 7 (as shown in FIG. 7b); When wiper arm 2 swings back, the backward horizontal force component Fh′ will convert the situation to become that the right side of the upper mounting channel 8 in the soft flexible upper support 4 of the blade body 6 will not be laterally affected by the right side of the metal vertebra 7 in detached manner while the left side of the upper mounting channel 8 will be laterally affected by the left side of the metal vertebra 7 in contact pushing manner (as shown in FIG. 7c and the hypothetical line of the 7d); Likewise, when wiper arm 2 swings back, the left side of the upper mounting channel 8 in the soft flexible upper support 4 will be deformed in stretchable manner due to squeeze by the by the left side of the metal vertebra 7 while the right side of the upper mounting channel 8 in the soft flexible upper support 4 will be deformed in a gap δ′ left between the right side of the upper mounting channel 8 and the right side of the metal vertebra 7 (as shown in FIG. 7e).
In other words, both of the deformed gap δ and gap δ′ between each of both sides of the upper mounting channel 8 and each of corresponding both sides of the metal vertebra 7 will be alternately created by the forward horizontal force component Fh and backward horizontal force component Fh′ from wiper arm 2 swinging back and forth. Consequently, the transmission delay of the exerting force due to both deformed gap δ and gap δ′ will cause a delay in temporary wiping pause and jerky phenomena of the rubber element 9 over the top surface of the windshield 3 so that a harsh scraping noise is incurred to spoil the tranquility in the vehicle. Moreover, because the swing frequency of the normal windshield wiper over the vehicle windshield 3 is 40˜50 times per minute, namely 2400˜3000 times per hour, the foregoing temporary wiping pause and jerky phenomena of the rubber element 9 over the top surface of the windshield 3 will follow in same frequency accordingly. Thus, the service life of the rubber element 9 in the windshield wiper will be shortened under such high frequency of temporary wiping pause and jerky phenomena and result in that the replacing frequency and cost is incurred to increase.
Inspecting and reviewing the foregoing drawbacks in the conventional windshield wiper of the prior art in the U.S. Pat. No. 7,210,189 patent, the primary cause is that the exerting force of the metal vertebra 7 from the wiper arm 2 indirectly apply on the semi-rigid lower support 5 via soft flexible upper support 4 instead of directly applying on the semi-rigid lower support 5. Therefore, the transmission delay of the exerting force due to both deformed gap δ and gap δ′ in the soft flexible upper support 4 is inevitable due to deformation susceptible soft flexible material so that a temporary wiping pause or delay with jerky phenomena of the rubber element 9 over the top surface of the windshield 3 is caused consequently. Thus, such bad structural design not only violates the transmission rule in dynamics but also bring bad effects aforesaid for the consumers.
Besides, the upper support 4 is made of soft flexible material while the vertebra 7 including upper mounting channel 8 therein is made of rigid metal so that friction resistance and assembling time are inevitably increased. Consequently, the incurred drawbacks are that the yield of mass production is reduced and the manufacturing cost is increased as well as marketing competition ability is decreased.